CHRIS Childs hopped up and down along the sidelines, cheering his team’s victory like a good bench warmer should. “People that know me know I’m an unselfish player,” he said. “All I care about is winning.”

Funny, Childs sounded more selfish than unselfish this week when he grumbled about his playing time or lack thereof. With Jason Kidd back in the lineup against the Sonics last night after missing two games with a groin injury, Childs fell even further out of the Nets’ rotation, his season ruined before it ever really began. The Nets are deep and dangerous without him.

Kidd started against the Sonics last night, but before long it was reserves Lucious Harris, Anthony Johnson, Aaron Williams and even Brian Scalabrine getting quality minutes. In the end, it was a monster game from Kenyon Martin (a career high 35 points) and the usual spectacular from Kidd (20 points, 12 assists) that helped the Nets win 109-108 in overtime after the Sonics’ Desmond Mason missed a 3-pointer at the buzzer.

“We had enough guys play well,” said Nets coach Byron Scott. “It shouldn’t have come down to a one-point win in overtime.” As the NBA season enters its second half, it’s the Nets’ depth that ultimately will set them apart from the rest of the Eastern Conference. Kidd’s brief absence has only strengthened the notion the Nets are really more about being a team than one great star. Nine players played and scored last night, none of them named Childs, who is buried behind Kidd, Johnson and Harris. It will be even more bleak for Childs when Dikembe Mutombo and Rodney Rogers return from injury.

If Childs was lobbying for more minutes by going public about “a lack of communication,” over his role, his strategy backfired. It only served to irritate Scott the way Martin was irritated by being left off the All-Star squad.

Truth is, the Nets have been irritated with Childs since he arrived for training camp 20 pounds overweight after signing a two-year contract worth $3.5 million last August. The Nets immediately sent him to the Duke University Diet and Fitness Center to lose weight.

His excuse for the excess poundage was his conditioning suffered while he was sidelined with an Achilles tendon injury. The Nets saw only a lack of self-discipline and dedication, two things Scott and GM Rod Thorn have been demanding since their arrival nearly three years ago. These are not the old Nets, for whom complaints and a lack of professionalism were a daily existence.

With Kidd sidelined, Childs thought he might finally get a chance to play substantial minutes. But he was quickly pulled from Friday’s game after not running the offense to Scott’s liking and hasn’t seen any action since. He recorded his second straight DNP last night, watching from the bench with his warmups on and a Gatorade towel around his neck.

Asked if he was looking forward to someday proving his worth, Childs said: “I don’t have to prove anything. I’ve played in this league enough years. It’s just a matter of staying focused and staying ready. There’s still a lot of time left. We’re not even at the All-Star break.”

Childs has always thought more of himself than what he has delivered. He signed a $25 million contract with the Knicks before the 1996-97 season to become their starting point guard. Within two years, he was coming off the bench, allowing Charlie Ward to assume a starting role, while Childs collected starter’s money.

There was little in Childs’ performance in his five seasons as a Knick that endeared him to Garden fans. So far, he’s headed for the similar ending with the Nets.